The present invention relates to an intraocular ring. More particularly, it relates to an intraocular ring to be worn inside of the equatorial area of a lenticular capsule (hereinafter called capsule) undergoing extracapsular cataract extraction (including phacoemulsification aspiration) for treatment of cataract in order to hold the capsule in a circular form.
Intraocular rings for retaining the shape of the capsule after extracapsular cataract extraction (including phacoemulsification aspiration) are roughly classified into the open ring as disclosed in Japanese Examined Patent Publication No. 51302/1993 (see FIG. 33 and FIG. 34), and the closed ring as disclosed in Japanese Examined Patent Publication No. 9582/1994 or Japanese Unexamined Patent Publication No. 364840/1992 (see FIG. 35, FIG. 36, and FIG. 37).
(1) It is an advantage of the open ring that the intraocular ring can be inserted easily into the capsule, but since the cut position of the ring is simultaneously movable, its demerit is that it is poor in the shape retaining property of the capsule following extracapsular cataract extraction (including phacoemulsification aspiration).
(2) In the case of a closed ring, after extracapsular cataract extraction (including phacoemulsification aspiration), as shown in FIG. 36 and FIG. 37, the capsule is filled up sufficiently with a viscous fluid, and an intraocular ring 100 is picked by forceps P (or injector (not shown) for soft lens) and deflected in a nearly rectangular shape, and the intraocular ring 100 is gradually inserted into the capsule through a cut S and a cut H. When inserted in the capsule, by the own elasticity of the intraocular ring 100, it restores the original annular shape and contacts with the whole circumference of the equatorial area of the capsule. Therefore, the closed ring is excellent in the shape retaining performance of the capsule after removal of the lens.
However, it requires a highly advanced skill in the operation of picking the intraocular ring 100 by the forceps P to deflect nearly in a rectangular form and inserting the intraocular ring 100 gradually into the capsule through the cut S and cut H, and it is difficult to insert the intraocular ring into the capsule. As compared with the open ring, yet, the cuts are larger, and troubles may be caused after operation (such as postoperative astigmatism).
On the other hand, European Patent Publication No. 0478929A1 discloses an intraocular ring (see FIG. 31 and FIG. 32) having a lock mechanism (locking achieved by inserting and engaging) 102 forming divided and plural step parts. In the case of this intraocular ring 100, after adjusting the diameter of the intraocular ring 100 by the lock mechanism 102, the intraocular ring 100 must be inserted into the capsule, and it cannot be inserted into the capsule in a divided state as in the above-mentioned open ring and the defects of the closed ring (2) are not solved.
Moreover, in the case of the intraocular ring disclosed in European Patent Publication No. 0478929A1, since the shrinking direction of the capsule and the ring size changing direction are identical, if a strong shrinkage occurs in the capsule, the ring size is also deformed. As a result, if part of the ring is adhered to the tissues, the original circular shape cannot be maintained but is deformed, which may lead to decentration of the intraocular lens.
It is hence an object of the invention to solve the problems of the prior arts, and present an intraocular ring, which is an open ring type intraocular ring when inserting, the intraocular ring capable of being inserted from small incision and, after being inserted into the capsule, is capable of obtaining a same compressive load as in the closed ring by engaging the engaging mechanisms having mutually complementary male and female structures provided at the ends of the intraocular ring.
The intraocular ring in one embodiment of the present invention is an intraocular ring made of an elastic material, defining a circular opening, and contacting with entire inner circumference of an equatorial area of a capsule after being inserted in the capsule, in which engaging mechanisms are provided at both ends, in a partially cut-off state of the intraocular ring, and a continuous ring shape without cut section is formed by engagement of the engaging mechanisms.
Preferably, the intraocular ring engaging mechanisms include mutually complementary male and female structures.
The intraocular ring in another embodiment of the present invention is a partially cut-off intraocular ring made of an elastic material, and contacting with entire inner circumference of an equatorial area of a capsule after being inserted in the capsule, in which a continuous shape is formed when the intraocular ring is inserted in the capsule as the both ends of the cut-off intraocular ring contact with each other.
Preferably, the both ends of the intraocular ring are formed in a taper.
The intraocular ring in still another embodiment of the present invention is an intraocular ring comprising two or three or more parts, made of an elastic material, and said intraocular ring contacting with entire inner circumference of an equatorial area of the capsule after being inserted in the capsule, in which the two or three or more parts individually have engaging mechanisms provided at both ends so that arbitrary adjacent parts may be engaged with each other in a male-female structure, and a continuous ring shape without cut section is formed when the two or three or more parts are mutually engaged with each other.
Preferably, a predetermined compressive load is applied in the engaged state of the cut sections of the ring, i.e., the ring is in elastic tension such that the ring would tend to reach the partially cut-off state, i.e. a discontinuous or open state.
Preferably, the compressive load is about 250 mgf or more.
Preferably, at least one end of both ends of the intraocular ring is provided with a flange, since circumferential or axial deviation of one end of the intraocular ring relative to the other end thereof is prevented.
An intraocular ring with an open ring shape for insertion is disclosed. It can be inserted from a small incision, and after inserting into the capsule, a compressive load nearly same as in the closed ring is obtained by engaging the engaging mechanisms having mutually complementary male and female structures provided at the ends of the intraocular ring.
Referring now to the accompanying drawings, the intraocular ring (hereinafter called the ring) of the invention is described in detail below.